Despite the inherently advantages of the box column, finding the best option for the I beam to the box column connection is the main challenge in using the box column as a structural member for special moment frames. ...Despite the inherently advantages of the box column, finding the best option for the I beam to the box column connection is the main challenge in using the box column as a structural member for special moment frames. In this paper, the seismic performance of urtreinforced connection, weakened connection and strengthened connection was evaluated through a comprehensive experimental program. The seismic comparisons were fabricated by assessing the strength, ductility and energy dissipation in each configuration. Three full scale tests with several connections were carried out. All the specimens were subjected to cyclic loading and prior to failure by forming a plastic hinge in the beam, all the connections managed to reach an inelastic rotation of more than 6.0% rad. The experimental and analytical results showed that the seismic performance of the strengthened connection with flange and shear plates turned out to be the most effective in the beam to the box column connection. Moreover, the normalized stress distribution of the continuity plates revealed that the possibility of the weld fracture in unreinforced connection is more than other specimens.展开更多
For a thin-walled box column with variable cross-section, the three governing equations for torsional-flexural buckling are ordinary differential equations of the second or fourth order with variable coefficients, so ...For a thin-walled box column with variable cross-section, the three governing equations for torsional-flexural buckling are ordinary differential equations of the second or fourth order with variable coefficients, so it is very difficult to solve them by means of an analytic method. In this paper, polynomials are used to approximate the geometric properties of cross-section and certain coefficients of the differential equations. Based on the energy principle and the Galerkin's method, the approximate formulas for calculating the flexural and torsional buckling loads of this kind of columns are developed respectively, and numerical examples are used to verify the correctness of the solutions obtained. The results calculated in this paper provide the basis for demonstrating the stability of thin-walled box columns with variable cross-section. This paper is of practical value.展开更多
A series of fundamental experimental investigation was conducted in order to examine the effect of PWHT by sheet-type ceramic heater on the residual stress, deformation and compressive behavior of non-stiffened welded...A series of fundamental experimental investigation was conducted in order to examine the effect of PWHT by sheet-type ceramic heater on the residual stress, deformation and compressive behavior of non-stiffened welded box columns. The sheet-type ceramic heater was able to control the required temperature history for PWHT with high accuracy. The welding-induced tensile and compressive residual stresses of the specimens were reduced by 90% and 76% respectively with PWHT. Besides, PWHT could reduce the welding-induced out-of-plane deformation by 22%. It was revealed that the PWHT specimens had a slight higher stiffness than the As-welded specimens when applying monotonic static compressive load on both As-welded and PWHT specimens. They could also enhance the ultimate compressive load capacity about 32% of that of the As-welded specimens. The effectiveness of PWHT with the sheet-type ceramic heater could be confirmed.展开更多
文摘Despite the inherently advantages of the box column, finding the best option for the I beam to the box column connection is the main challenge in using the box column as a structural member for special moment frames. In this paper, the seismic performance of urtreinforced connection, weakened connection and strengthened connection was evaluated through a comprehensive experimental program. The seismic comparisons were fabricated by assessing the strength, ductility and energy dissipation in each configuration. Three full scale tests with several connections were carried out. All the specimens were subjected to cyclic loading and prior to failure by forming a plastic hinge in the beam, all the connections managed to reach an inelastic rotation of more than 6.0% rad. The experimental and analytical results showed that the seismic performance of the strengthened connection with flange and shear plates turned out to be the most effective in the beam to the box column connection. Moreover, the normalized stress distribution of the continuity plates revealed that the possibility of the weld fracture in unreinforced connection is more than other specimens.
文摘For a thin-walled box column with variable cross-section, the three governing equations for torsional-flexural buckling are ordinary differential equations of the second or fourth order with variable coefficients, so it is very difficult to solve them by means of an analytic method. In this paper, polynomials are used to approximate the geometric properties of cross-section and certain coefficients of the differential equations. Based on the energy principle and the Galerkin's method, the approximate formulas for calculating the flexural and torsional buckling loads of this kind of columns are developed respectively, and numerical examples are used to verify the correctness of the solutions obtained. The results calculated in this paper provide the basis for demonstrating the stability of thin-walled box columns with variable cross-section. This paper is of practical value.
文摘A series of fundamental experimental investigation was conducted in order to examine the effect of PWHT by sheet-type ceramic heater on the residual stress, deformation and compressive behavior of non-stiffened welded box columns. The sheet-type ceramic heater was able to control the required temperature history for PWHT with high accuracy. The welding-induced tensile and compressive residual stresses of the specimens were reduced by 90% and 76% respectively with PWHT. Besides, PWHT could reduce the welding-induced out-of-plane deformation by 22%. It was revealed that the PWHT specimens had a slight higher stiffness than the As-welded specimens when applying monotonic static compressive load on both As-welded and PWHT specimens. They could also enhance the ultimate compressive load capacity about 32% of that of the As-welded specimens. The effectiveness of PWHT with the sheet-type ceramic heater could be confirmed.
